Native vs Non Native gardening

Giant Swallowtail Butterfly on a Zinnia – the flower is definitely not native to Southern Ontario

I recently started following the Royal Horticultural Society on Twitter (@The_RHS); I’m not sure how this feed came to my attention, likely it was Twitter itself, that clever creature, that suggested it.  It was a good suggestion.  Even though it’s a British organization, and the information they share is abut British gardening and British plants and British garden shows, the RHS does, not infrequently, post tidbits that are relevant over here.  Also, their picture are very pretty.

This morning the Society tweeted that the second paper from their Plants for Bugs program has at long last been published.  (The first paper was published in 2015.)

Plants for Bugs is a “a four-year study into wildlife gardening, which was undertaken at RHS Garden Wisley in Surrey…”  as in England, just southwest of London.  The scientists set out to determine what sort of plant typically found in an English garden does best at attracting insects: native or non-native.

Garden commentators in North America have, for many years now, been battling it out (sometimes quite heatedly) over this question.  There are extreme gardeners who ONLY plant natives and those who couldn’t give a whit if a plant is native or not, as long as it looks pretty.  Most commentators fall in the middle – wanting to use natives when possible but not closing the door to aliens (aka non-native plants).

The arguments for using natives run along the lines of they are more drought tolerant (true, but only if it’s a drought tolerant plant to begin with: you wouldn’t stick a native Marsh Marigold – Caltha palustris – in gravelly soil on a south slope); they’re better suited to our climate (until you factor in climate change and how Prince Edward County’s Plant Hardiness Zone has gone from zone 5b to zone 6a in the past 20 years); and they provide better food – nectar, pollen and roughage – than non-natives.

It’s this last assumption that the folks in England wanted to measure.  In 2009, they created 36 planting beds, each nine square metres, and planted some with a mix of plants native only to the UK; other plots had plants that only grow elsewhere in the northern hemisphere while the rest had plants that grow in the southern hemisphere.  Then they waited, and counted the invertebrate life that showed up.

“By the end of December 2013 (four full years of recording) approximately 80,000 invertebrates had been counted and more than 300 species identified.”

The peer reviewed papers that have so far resulted from the study have led the RHS to come up with key messages for the home gardener.  To quote from the RHS site:

From the first paper, that studied pollinating insects:

• The best strategy for gardeners wanting to support pollinating insects in gardens is to plant a mix of flowering plants from different countries and regions.
• Emphasis should be given to plants native to the UK and the northern hemisphere, though exotic plants from the southern hemisphere can be used to extend the season
• Regardless of plant origin (native or non-native), the more flowers a garden can offer throughout the year, the greater the number of bees, hoverflies and other pollinating insects it will attract and support.

From the second paper, that studied insects that chomp on plants, suck the juices from plants or eat other bugs that suck or chew:

• The best strategy for gardeners wanting to support plant-associated invertebrates is to plant a predominance of plants native to the UK.
• Plants native to the Northern hemisphere are likely to support only marginally fewer (less than 10%) invertebrates in some functional groups (including herbivores and some predators) than UK native plant schemes. And exotic plant schemes based on Southern hemisphere plants will still support a good number of invertebrates, albeit around 20% fewer than plants from the UK.
• Regardless of plant origin, the more densely your garden is planted or allowed to grow, the greater the abundance of invertebrates of all kinds (herbivores, predators, detritivores and omnivores) it will support.

 

I’m guessing these messages will appeal to many North American gardeners as well.

For me, the takeaway is to plant densely using a diverse mixture of annuals, perennials, shrubs and bulbs to create as long a flowering season as possible.

Sunday Surprise

I’m seriously serious about composting.  Almost the first thing we did after buying our Prince Edward County property was build this huge compost bin.  I think I had seen something like it on a BBC gardening show.  I think we had fantasies of being able to drive the shovel of a small garden tractor into the bins to turn the stuff over.  No more using shovels or pitchforks for me.

Oh well.

The system works, in its own way, like a charm, (my) manual labour involved notwithstanding.  There’s no water where it’s situated at the back of the field so it generally takes longer for plant material to break down than it did in my small city black plastic with a lid composter.  But that’s OK because I have three bins to work with.

The first year I pile new stuff in one bin, filling it to the top by the end of the season.  The next year I start fresh with the next bin and let the first  just sit there, using a heavy fork to turn stuff over every now and then, to get air to the bottom of the pile.

I start the third year by screening the first year’s material – dumping finished compost in the third bin, and putting the unfinished stuff in the second bin to continue breaking down.  This leaves me with the first bin empty and ready to use.

Sounds complicated but it’s not.  Until this year.  Mid May something sprouted in the middle bin. Now, a lot of things sprout in the compost bins — tomato seedlings, Rudbeckia, various weeds, garlic, Virginia Creeper…but this one plant seemed to have strength and purpose.  It became large very quickly and was obviously some sort of squash so I left it alone.  I like squash.  And I loved the huge leaves this vine produced – so much larger than the leaves of anything I had ever purposefully planted!  And by mid July it was obvious – it was a pumpkin vine. I had grown pie pumpkins last year and one seed survived the winter.

So now I have a withering vine (it is August after all, and it’s been rather dry the past few weeks) and six good sized pie pumpkins growing.  And I notice, on Saturday, a large burrow going into the middle compost head, directly under where the pumpkin sprouted.  It looked like it could have been made by a skunk or a fox, hopefully not by a rat!

On Sunday I went out back to dump kitchen scraps and the whole centre of the compost pile had been torn out.  There, in a hole in the middle, was this.  I very quickly left the immediate vicinity.  And spent the day puzzling about what creature in our back field was brave enough or big enough to attack such a huge nest.

 

Time to revel in Rudbeckia

When I first started gardening (eons ago, it seems) in my tiny Toronto backyard, one of the first flowers I bought was a Black Eyed Susan.  It was lovely – small, hairy leaves with bright orange-yellow flowers in late summer.  I planted it in an area that started out in full sun but gradually, as surrounding trees grew, became shady, which is when I transplanted a chunk of it to the County.  Turns out this was Rudbeckia fulgida var. sullivantii ‘Goldsturm.’  I didn’t know the Latin name then, and didn’t know how many Rudbeckia species were out there and available.

Turns out there are a lot!  At least 25 accepted species with a lot of different common names that can be confusing – one of the reasons I like to use botanical (Latin) names as much as possible.

R. hirta & R. fulgida in same patch

 

In my garden they start blooming in earnest the second week of August and will continue until mid September, longer if dead-headed.  The different species have different ways of spreading — R. hirta and R. fulgida will quickly spread by underground runners as well as self-seeding.

 

 

Rudbeckia laciniata

My favourite tall Rudbeckia (one of my favourite perennials in general) is Rudbeckia laciniata.   I’ve read where it likes moist areas, stream beds and such, but I find that they send their seeds everywhere and will grow everywhere, even in the driest areas of the yard.  They can grow to five or six feet tall but the neat thing is you can, in early summer, clip them back by half or more (as you may do with Asters and Solidago – Goldenrod) so that you keep a clump bushy and shorter.

 

The shorter Rudbeckia‘s do want water — this is after a month with no rain.  The plant came back (you can see new leaves poking through) in the fall but all the flower buds dried to a crisp in the summer.

fun with photoshop…

The Zinnias are HUGE this year!

Highs and Lows

An e-mail last week from my dad on Vancouver Island had a photo attached of his gigantic Rose of Sharon (Hibiscus syriacus) – its first flower had opened, a lovely pure white with a burgundy red eye.  Three days ago my own Rose of Sharon bloomed for the first time ever, and it’s remarkably similar to my dad’s!  My still tiny shrub was purchased at a yard sale last spring – it looks to have a dozen or so flower buds – I’m looking forward to future years when it’ll be as large as the one in B.C. – I’ve heard that hummingbirds love them!

 

 

My glorious stand of pastel hued Hollyhocks (Alcea rosea) was no match for the strong winds we had last weekend….they toppled over as one, snapping several of the tallest stalks.  I collected a few seed pods that I hope are ripe enough before cutting them off and adding them to the burn pile (don’t want to risk spreading rust through the compost pile).  I was able to tie up a half dozen or so to continue their display for a few more weeks and provide enough seeds for sowing and sharing.

Fun fact – both the Hollyhock and Rose of Sharon are members of the Mallow family (taxonomically speaking).  And in the same area of the garden as these Hollyhocks and Rose of Sharon is the perennial commonly called Mallow (Malva moschata)– it arrived uninvited but has made for a very long lasting display of beautiful pink flowers all summer.  They’re blooming in white or pink in several places around the yard and make a great filler.

mid summer report – happy happy joy joy

Nothing has died.

That kind of says it all.  This time last year the fields were brown, the Larix were dead, the Rudbeckia was just not flowering.

Copious amounts of rain this spring and an average amount so far this summer has brought in the garden great joy to all things growing and, I suspect, all things crawling and slithering and hopping (hello newly arrived rabbit family!) as well.

Here are a few updates from previous posts.

The Canadian Burnet (Sanguisorba canadensis) purchased and planted on July 1 is now blooming:

The Cup Plant (Silphium perfoliatum) started from seed and planted out last year is now eight feet high and blooming:

Garlic planted last fall has been harvested, and my experiment to see if cutting off the scapes does increase bulb size shows me yes, it does:

left – scape cut off; right – scape not cut off

Veggies are all doing well with no or minimal watering – have harvested beans, chard, zucchini, green onions; the spaghetti squash and tomatoes are getting plump:

This Phlox, given by friends, almost didn’t make it last year.  So glad it hung in to produce this glorious display now:

Directions from Nature

When early pioneers were rolling their way across the tall grass prairies of North America, sometimes, in mid summer, they would come across a towering plant with huge basal leaves that often were oriented on a north-south axis.  They called it a Compass Plant.  In later years scientists speculated the leaves point that way to protect themselves from the burning sun.  The plant would be labelled Silphium laciniatum – the same genus as the Cup Plant (Silphium perfoliatum) that I wrote about earlier.

It’s easy to see why – they’re both really tall (the Compass Plant can grow to 12 feet high) and both has relatively small (2″ – 4″) sunflower-like flowers.  Carious types of bees love to feed in the flowers and their stalks, if left up all winter, can provide over-wintering refuge for beneficial insects as well.  They differ in that the Cup Plant likes moist meadows and tolerate flooding in spring while the Compass Plant, being native to the prairie, likes it dry and can tolerate drought.  (After next to no rain during last year’s spring and summer drought, they’ve back in my dry back field more vigorous than ever.)

This is likely because Compass Plants have a really long taproot (up to 16′ deep in the prairies!)  that seeks out moisture, even in the rocky, decidedly non-prairie like soil of the County.  This root can, unfortunately, make it really challenging to transplant – best to start seeds and plant them where they can stay for many years.  They can self-seed but it’s not a fast process – my 15 year old patch has produced only three offspring that I know of, two in the gravelly rocky area where the ‘parents’ live and one in a meadow, about 30 feet away.  One plant with a single flowering stalk can, however, become one plant with multiple flowering stalks.

If you can find Compass Plant for sale (perhaps at a local native plant nursery)  and you have room, buy it; or, if you find seeds somewhere (Seedy Saturdays in Picton or Trenton possibly) , try starting them yourself.  (Read up on how to prepare them for sowing first.)